1. Field of the Invention
The present invention is related to a Front Opening Unified Pod (FOUP), and more particularly, to a latch component deployed in the door of FOUP.
2. Description of the Prior Art
The semiconductor wafers need to be transferred to different work stations to go through various processes in required equipments. In order to facilitate the transferring of wafers and to prevent the pollution of wafers from occurring during transferring process, a sealed container is provided for the automatic transferring process. Referring to FIG. 1, which is a view of wafer container of the prior art. The wafer container is a Front Opening Unified Pod (FOUP) which includes a container body 10 and a door 20. The container body 10 is disposed with a plurality of slots 11 for horizontally receiving a plurality of wafers (not shown in Figure), and an opening 12 is located on a sidewall of the container body 10 for importing and exporting the wafers. The door 20 further includes an outer surface 21 and an inner surface 22, wherein the door 20 is joined with the opening 12 of the container body 10 via the inner surface 22 to protect the plurality of wafers within the container body 10. Furthermore, at least one latch hole 23 is disposed on the outer surface 21 of the door 20 for opening or closing the wafer container. According to the aforementioned, due to that the wafers are horizontally placed in the container body 10, thus, a wafer restraint component is needed in the FOUP to prevent the wafer from displacement or from movement toward the opening 12 of container body 10 to occur during the wafer transferring process due to vibration.
Referring to FIG. 2, which is a view of the door of FOUP disclosed in U.S. Pat. No. 6,736,268. As shown in FIG. 2, the inner surface 22 of door 20 is disposed with a recess 24, which extends from the top end 221 of the inner surface 22 to the bottom end 222 and is located between the two latch components 230 (within the door). The wafer restraint module consisting of two wafer restraints 100 set aside each other is further disposed in the recess 24. Each wafer restraint 100 further includes a plurality of wafer contacts 110 for sustaining corresponding wafers to prevent the wafers from being displaced or moving toward the opening of the container body due to vibration during the transferring process. However, the aforementioned wafer restraint module is disposed in the recess 24 of the inner surface 22 of the door 20, and thus the wafers are merely attached to the inner surface 22 of the door 20 or partially settled down within the recess 24. As a result, the wafers cannot be securely and fully settled into the recess 24 in order to effectively shorten the length between the front side and the back side of the FOUP. In addition, dust particles generated due to the friction between the wafer restraint module and the wafers can be easily accumulated in the recess 24. In the process of cleaning the accumulated dust particles, it is necessary to separate the wafer restraint module from the recess 24 on the inner surface 22 of the door 20. Frequent separation and re-assembly of the wafer restraint module thus causes the wafer restraint module to slacken easily.
Furthermore, FIG. 3 is a view of latch component 230 in the door 20 of a Front Opening Unified Pod (FOUP) as described in U.S. Pat. No. 5,711,427. The method for assembling door 20 and container body 10 is mainly to dispose movable bolts 231 on the two sides of door 20, i.e. between outer surface 21 and inner surface 22, and to dispose socket holes 13 (referring to FIG. 1) near the edge of opening of door 10 for corresponding to the bolts 231. The objective of fixing door 20 in the container body 10 can thus be achieved with the rotation of latch hole 23 (referring to FIG. 1) disposed on the outer surface 21 of door 20 that leads to the insertion of latch bolts 231 into socket holes 13, wherein the insertion and withdrawal of bolts 231 is controlled by the rotation of latch hole 23 via a round-shaped cam 232.
And in the actual operation of semiconductor factory, the opening of FOUP is mainly operated through a Wafer Load Port, which comprises at least a latch key. The latch key of this Wafer Load Port is inserted into the latch hole 23 on the outer surface 21 of the door of FOUP for rotating the round-shaped cam 232 and thus driving the movable latch bolts 231 to open or close the FOUP. In addition, according to the SEMI standards, the size of latch key and the size of latch hole are standardized. However, in a FOUP designed according to the required standards, an arrestment error of 9.44 degrees will occur when the corresponding latch key and latch hole are rotated. Therefore, when the FOUP is horizontally placed, if the error is more than 9.44 degrees, the latch key is not able to rotate the latch hole to operate the cam and thus the door cannot be successfully opened.
In addition, other U.S. patents that describe latch component in door of FOUP include U.S. Pat. Nos. 5,915,562, 5,957,292, 6,622,883, and 6,902,063. In order to achieve air tightness when joining the door and the container body, the movable bolts of latch component will shift longitudinally for fastening a springy air-tight component, which leads to achievement of both objectives of closing FOUP and achieving air tightness. However, in prior latch patents, complex mechanic apparatuses are used, which not only result in higher failure rate but also generate too much mechanical friction in the operating process that pollutes wafers. Moreover, the air tightness achieved by fastening springy air-tight component with shift of movable bolts cannot sustain for very long time and is not effective enough.
Moreover, in conventional FOUP, some restraint components are disposed on the inner surface of door 20. Thus when the door 20 closes container body 10, the restraint components contact wafers and completely fix the wafers in order to prevent displacement of wafers in FOUP from happening during transferring procedure. And in order to avoid too forceful collision or friction between restraint components and wafers when contacting, therefore, as shown in FIG. 4, a few U.S. patents disclose springy component 86 that is disposed between cam 232 in latch component 230 and door 20. In the process in which cam 232 rotates and drives movable bolts 231 to close FOUP, this springy component 86 can function as damping for restraint component disposed on inner surface of door 20 to contact wafers under mitigated and smooth condition, and thus the problem of collision and friction can be solved. U.S. patents related to such design include U.S. Pat. Nos. 6,880,718, 7,168,587, and 7,182,203. However, when this way of laterally driving is employed, it is easy for an offsetting force to generate on the moving direction of movable bolts 231, which causes failure of insertion of movable bolts into socket holes 13 of container body 10. Thus, container body 10 and door 20 cannot be closed, and more problems in the production occur.